I have an upcoming Oktobefest party. I've been debating if I should have hefeweizen or dunkelweizen on tap at my party. I came up with a solution of having both but only brewing once!? Please tell me if you think this would work....

Cold steeping would definitely cut down on the roasty flavors and astringency related to highly kilned grains - that being said I would personally use more carafa III (special) in the cold-steep blend than any of the others listed just to make sure I primarily get color and not roast. I would probably do a 1/3: choco wheat/carafa